Adhesive tape for wafer thinning and preparation method therefor, and wafer grinding method

Abstract

Disclosed in the present invention are an adhesive tape for wafer thinning and a preparation method therefor, and a wafer grinding method. The adhesive tape for wafer thinning comprises an adhesive tape layer, a base film layer, and a conductive coating, which are sequentially stacked, wherein the base film layer and the conductive coating constitute an antistatic base film; the raw materials of the adhesive tape layer comprise an acrylic adhesive, a hardening agent and an antistatic agent, the mass dosage of the hardening agent being 3-4% of that of the acrylic adhesive, and the mass dosage of the antistatic agent being 1-2% of that of the acrylic adhesive; the base film layer is selected from a TPU film; and the conductive coating is selected from a silver nanowire coating. The adhesive tape for wafer thinning of the present invention can be applied to wafer grinding, has good antistatic property, and can effectively inhibit stripping static electricity; in addition, the adhesive tape further has the advantages of being stripped without residue and having water seepage prevention.

Description

Adhesive tape for wafer thinning, preparation method thereof and wafer grinding method

[0001] The present application relates to the field of semiconductor wafer processing technology, and in particular to a wafer thinning tape, a preparation method thereof, and a wafer grinding method. Background Art

[0002] During the wafer grinding process, wafer thinning tape is typically applied to the non-ground surface of the wafer to protect structures such as copper pillars and solder balls. While this tape provides ample protection for the wafer, it also acts as a buffer, mitigating vibrations generated during grinding. After grinding, the tape must be peeled off the wafer surface. This generates peeling static electricity, which can affect wafer performance. Therefore, a wafer thinning tape that can suppress this static electricity is needed. Summary of the Invention

[0003] The purpose of the present application is to provide a wafer thinning tape, a preparation method thereof and a wafer grinding method, wherein the wafer thinning tape can significantly suppress peeling static electricity.

[0004] To achieve the above-mentioned purpose, an embodiment of the present application provides, on the one hand, a tape for wafer thinning, comprising a tape layer, a base film layer, and a conductive coating stacked in sequence, wherein the base film layer and the conductive coating constitute an antistatic base film; wherein the raw materials of the tape layer include acrylic adhesive, a hardener and an antistatic agent, the mass dosage of the hardener is 3%-4% of the acrylic adhesive, and the mass dosage of the antistatic agent is 1%-2% of the acrylic adhesive; the base film layer is selected as TPU film; and the conductive coating is selected as nano silver wire coating.

[0005] The hardener is selected to be compatible with the acrylic adhesive, the TPU film is a thermoplastic polyurethane film, the nano silver wire is a one-dimensional structured metallic silver, and the base film layer and the conductive coating constitute the ESD TPU film.

[0006] In some embodiments, the tape layer has a thickness of 10-50 microns.

[0007] In some embodiments, the base film layer has a thickness of 100-500 microns.

[0008] In some embodiments, the impedance of the antistatic base film is preferably not greater than 10 2 Ohm / square, the impedance of the antistatic base film is affected by the thickness of the conductive coating, and the impedance can be adjusted by adjusting the thickness of the conductive coating.

[0009] In some embodiments, the hardener is preferably toluene diisocyanate.

[0010] In some embodiments, the antistatic agent is preferably an alkyl-alkylpyridinium salt of a polyhalo-[(polyhaloalkylsulfonyl)]alkanesulfonamide.

[0011] In some specific embodiments, the silver nanowires used in the silver nanowire coating are preferably silver nanowires with a diameter of 25-300 nanometers and a length of 10-300 micrometers.

[0012] Another aspect of the present application provides a method for preparing the wafer thinning tape. The method adopts a coating process and includes:

[0013] Mixing acrylic adhesive, hardener and antistatic agent in parts by mass to obtain a tape layer slurry;

[0014] Applying a tape layer slurry on the release film and drying it to form a tape layer on the release film;

[0015] Coating nano silver wires on one side of the base film layer and drying to form a conductive coating on the surface of the base film layer;

[0016] The tape layer is attached to the other side of the base film layer to obtain the wafer thinning tape.

[0017] In some specific embodiments, both coating the tape layer slurry and coating the nano silver wires are completed using a coating machine.

[0018] On the other hand, an embodiment of the present application provides a wafer grinding method, comprising: firstly adhering the tape layer of the above-mentioned wafer thinning tape to the non-grinding surface of the wafer, and then grinding the wafer.

[0019] When wafer grinding is performed, the wafer thinning tape of the present application is adhered to the non-grinding surface of the wafer to protect the non-grinding surface. At the same time, the wafer thinning tape also plays a role in controlling the uniformity of the grinding thickness and has a stress buffering effect.

[0020] Compared with the prior art, this application also has the following features and beneficial effects:

[0021] The wafer thinning tape of the present application has excellent antistatic properties and can effectively suppress static electricity during peeling; it also has the advantages of leaving no residue after peeling and preventing water seepage. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and beneficial effects of this application more clear, this application is further described in detail below in conjunction with embodiments.

[0023] Several examples are provided below, and the raw materials used in the examples are as follows:

[0024] Acrylic adhesive: Nanbao resin TP-911, solid content 40±1%;

[0025] Hardener: ingredient toluene-2,4-diisocyanate, its structural formula is ;

[0026] Antistatic agent: IL-P series antistatic agent can be selected. In this embodiment, IL-P14 from the IL-P series antistatic agent is selected. Manufacturer: Japan Guangrong Chemical; main ingredient: alkyl-alkyl pyridinium salt of polyhalogenated-[(polyhalogenated alkylsulfonyl)]alkanesulfonamide;

[0027] TPU film: commercially available, thickness 150 μm, film surface impedance 2*10 13 Ohm / sq;

[0028] Nano silver wire: Haoshen Fiber Technology FN03, nano silver wire average length 5 microns-20 microns, average diameter 45 nanometers, solid content 1%-10%.

[0029] The components and amounts in the examples of this application are shown in Tables 1-3. The performance of the adhesive tapes obtained in the examples in Tables 1-3 was tested as follows.

[0030] Adhesion test: Refer to ASTM D3330 for adhesion test;

[0031] Impedance test: Refer to standard ASTM D257 to test the surface impedance of TPU film and the surface impedance of tape layer;

[0032] Peel-off static electricity test: The tape layer is attached to a wafer and peeled off at a 180-degree peel angle and a speed of 1000 mm / min. The maximum static electricity voltage generated at the moment of peeling is measured using an electrostatic meter fixed above the wafer, which is the peel-off static electricity voltage.

[0033] Water permeability test: Attach the tape layer to the wafer, soak the wafer in 40°C water for 1 hour, remove the wafer and observe whether water has seeped between the tape and the wafer.

[0034] Table 1. Formulation and performance parameters of tape layer without antistatic agent

[0035]

[0036] According to the formula provided in Table 1, an acrylic adhesive and a hardener were mixed in parts by weight to form a slurry. This slurry was then applied to a release film using a film coater. After drying, a 20-micron thick tape layer was formed on the release film. The tape layer was then attached to a wafer, and the adhesive strength and water permeability of the tape layer, as well as the residue left when the tape was peeled off, were tested. Performance parameters are listed in Table 1. The performance parameters in Table 1 show that the acrylic adhesive has an adhesion strength of approximately 1000g / 25mm. The addition of a hardener affects the adhesive strength, residue, and water permeability of the acrylic adhesive. Only when the hardener content is 3% to 4% of the acrylic adhesive, preferably 3%, can good adhesion be achieved while also achieving excellent water permeability and leaving no residue when peeled off.

[0037] Table 2 Formulation and performance parameters of tape without conductive coating

[0038]

[0039] According to the formula provided in Table 2, an acrylic adhesive, a hardener, and an antistatic agent were mixed in parts by weight to form a slurry. This slurry was then applied to a release film using a film coater. After drying, a 20-micron thick tape layer was formed on the release film. The surface impedance of the tape layer was then measured. The tape layer was then laminated to the surface of a TPU film to produce a tape without a conductive coating. The resulting tape layer was applied to a wafer, and the adhesive strength, residual strength, and peeling static voltage were measured. To minimize environmental influences on the peeling static test results, the peeling static voltage was tested at an ambient temperature of 25°C and a humidity of 50%. Performance parameters are listed in Table 2. As shown in Table 2, the addition of an antistatic agent can reduce peeling static electricity, but excessive amounts can affect adhesion and peeling residue. When the antistatic agent is used in an amount of 0.5%-2% (preferably 1%-2%) of the acrylic adhesive, good antistatic properties, good adhesion, and zero peeling residue are achieved.

[0040] According to the formula provided in Table 3, acrylic adhesive, hardener and antistatic agent are mixed in parts by mass to obtain a slurry; the slurry is coated on a release film using a coating agent, and a tape layer with a thickness of 20 microns is formed on the release film after drying. Nanosilver wires are coated on one side of the base film layer, and a conductive coating is formed on the base film layer after drying to obtain an ESD TPU film. The ESD TPU film is an antistatic base film, and the film surface impedance of the ESD TPU film is tested. The tape layer is attached to the other side of the base film layer to obtain a tape for wafer thinning. The tape layer of the obtained tape is attached to the wafer, and the residual situation and the peeling static voltage when the tape is peeled off are tested. To avoid the influence of the environment on the peeling static test results, the peeling static is tested at an ambient temperature of 25 degrees and an ambient humidity of 50% RH. The performance parameter data are listed in Table 3.

[0041] Table 3 Formulation and performance parameters of wafer thinning tape

[0042]

[0043] Combining Tables 2 and 3, it can be seen that while a greater amount of antistatic agent improves the effectiveness of suppressing peel static, excessive antistatic agent addition can cause residual precipitation in the tape layer, affecting adhesion. Therefore, attempting to achieve excellent antistatic effects solely through antistatic agent will compromise the tape's overall performance. However, using a specific amount of antistatic agent in combination with an ESD TPU film can achieve excellent peel static suppression while also maintaining the tape's overall performance. When the tape is peeled from the wafer, the antistatic agent in the tape layer exerts a certain antistatic effect, reducing static electricity generation. Combined with the low impedance of the ESD TPU film, this induces electrons to migrate toward the low-impedance surface of the ESD TPU film, resulting in a significant peel static suppression effect.

[0044] The above embodiments are merely for the purpose of illustrating the embodiments and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications may be made based on the above descriptions. It is not necessary and impossible to enumerate all implementation methods here. Therefore, any obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A wafer thinning tape, characterized in that: It comprises a tape layer, a base film layer and a conductive coating layer stacked in sequence, wherein the base film layer and the conductive coating layer constitute an antistatic base film; The raw materials of the tape layer include acrylic adhesive, hardener and antistatic agent, the mass amount of the hardener is 3%-4% of the acrylic adhesive, and the mass amount of the antistatic agent is 1%-2% of the acrylic adhesive; The base film layer is a TPU film; The conductive coating is a nano silver wire coating; The hardener is toluene-2,4-diisocyanate; The antistatic agent is selected from alkyl-alkylpyridinium salts of polyhalogenated-[(polyhalogenated alkylsulfonyl)]alkanesulfonamide.

2. The wafer thinning tape according to claim 1, wherein: The tape layer has a thickness of 10-50 microns.

3. The wafer thinning tape according to claim 1, wherein: The base film layer has a thickness of 100-500 microns.

4. The wafer thinning tape according to claim 1, wherein: The impedance of the antistatic base film is not greater than 10 2 Ohm / sq.

5. The wafer thinning tape according to claim 1, wherein: The nano silver wires used in the nano silver wire coating have a diameter of 25-300 nanometers and a length of 10-300 micrometers.

6. The wafer thinning tape according to claim 5, characterized in that: The nano silver wires used in the nano silver wire coating have an average diameter of 45 nanometers and an average length of 5-20 micrometers.

7. The method for preparing the wafer thinning tape according to any one of claims 1 to 6, characterized in that: include: Mix the acrylic adhesive, hardener and antistatic agent according to parts by mass to obtain a tape layer slurry; Applying a tape layer slurry on the release film, and drying to form a tape layer on the release film; Coating nano silver wires on one side of the base film layer, and forming a conductive coating on the surface of the base film layer after drying; The tape layer is attached to the other side of the base film layer to obtain the wafer thinning tape.

8. A wafer grinding method, characterized in that: include: First, the tape layer of the wafer thinning tape according to any one of claims 1 to 6 is attached to the non-polishing surface of the wafer, and then the wafer is polished.

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